Buccal drug delivery adhesion

Sustained adhesion of the dosage form (tablet, patch) to the mucosa is an important first step to successful buccal delivery. The mucus plays an important role during this mucoadhe-sive process by buccal drug delivery systems. The interaction between the mucus and mucoadhesive polymers generally used in most dosage forms can be explained by theories summarized in Table 9.1. 

Studies on the effect of carrageenan and other colloids on muco-adhesion of drugs to the oropharyngeal areas have shown that carrageenan had the greatest propensity for adhesion and can be used in formulations for oral and buccal drug delivery. 

Anders R, Merkle HP. Evaluation of laminated muco-adhesive patches for buccal drug delivery. Int J Pharm 1989 49 231-240. 

Special formulations are now in development to provide prolonged mucosal adhesion and sustained delivery of drug through the buccal membrane. Such formulations comprise flexible adhesive patches and films. Important features for drug delivery associated with these novel buccal patches include ... 

However, the action of saliva and the continuous swallowing thereof tends to wash away drugs applied to the mucosa, resulting in short retention time and low therapeutic efficacy. Therefore, proper design of a dosage form for use in the oral cavity is necessary [23], and to overcome some of these shortcomings, a buccal adhesive system of drug delivery has been developed and is under continued research for improvement [26,24,25]. 

J.D. Smart, Drug delivery using buccal-adhesive systems, Adv. Drug Delivery Rev., 11, 253-270,1993. 

Buccal dosage forms can be of the tablet, patch, gel, or ointment type and can be employed for local or systemic delivery. For local deliveiy, conventional dosage forms such as solutions and various types of tablets (immediate release, effervescent, etc.) are more suitable. These forms generally have uncontrolled drug release with subsequent variable absorption and short residence times, and may not provide sufficient bioavailability. Novel dosage forms such as adhesive tablets, patches, gels, and... 

The above procedure was also employed to investigate buccal absorption from the HEMAC experimental delivery device. As in the case of the diffusion cell the drug-loaded disc was positioned on the inner central surface of the buccal mucosa. An impermeable film coated with mucosal adhesive (F-4000, Adhesives Research, Glen Rock, PA) on the periphery was then positioned over the HEMAC disc to prevent dehydration and to secure the device in place on the mucosal surface. The disc was allowed to remain in contact with the mucosa for 4 h before it was removed for quantitation of residual drug content. Blood samples were collected over the same interval as for the saturated solution and processed in the same manner. 

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